Scan dates / gestational age

[Soontobemummy9]

Hello,
I am hoping someone can help me understand a couple things.
I am currently 29 weeks pregnant, I fell pregnant with my partner really quick (we met in march and I found out I was pregnant in May). When I first find out I was over the moon and once I got past the anxiety of the 12 weeks a thought popped into my head one day and has never left. I thought what if the baby isn’t my partners, now I have no reason to believe this but I can’t get the thought out of my head. I already suffer from OCD (I’ve had this since I was 15, checking doors, taking pictures of the oven etc). I think what I’m having is an intrusive thought which is taking hours of my day.
Im on the list for CBT and I am waiting on a call from the perinatal health team, as this thought has caused so much anxiety and has ruined my pregnancy.
im not sure why I have this thought, my mum passed away when I was a week old due to child birth and I’m not sure if that’s something playing on my mind making me feel anxious. Has anyone else felt like this or am I completely crazy??
I wanted to know, if I have a scan and it says gestational age 12 weeks, does that mean I am actually 10 weeks pregnant?
i know the baby is my partners but I’m constantly looking for a reassurance, I’m tired from constantly questioning myself and feeling like I’m going crazy and that I should feel guilty for something that isn’t true.
sorry for the long paragraph, I’m just hoping someone can help me.

Hi OP - sorry that you’re going through all of this. Really hope the referrals and help comes through soon. If on a scan it says 12 weeks, then you most likely conceived 10 weeks before. The first 2 weeks of a pregnancy (2/40) you would not be pregnant for and it would be prior to ovulation and fertilisation. Dating (and the 40 weeks of pregnancy) is calculated from the first date of your last period and obviously you would not be pregnant during your period or immediately after. I hope that helps slightly x

Hello,
thank you for your reply! I was just getting confused as to why the scan would also add two weeks on even though you’re not pregnant for the full 12 weeks.
I’m hoping I’ll hear something soon, I had my fist initial CBT call and they confirmed I’m extremely anxious (I got 20/21) I think it’s just all a mixture of getting pregnant really quick before I was ready and being in a new relationship, along with the anxiety of what happened to my mum.
thank you again for your reply xx

They've kept the dating of a pregnancy in line with the first day of your last period - as years and years ago that was the only way to date a pregnancy. Obviously that means you're not at all pregnant for the first 2 weeks, and not everyone ovulates on day 14 of their cycle so it doesn't fit perfectly anyway.
The USS is much more accurate, so if you take 2 weeks off the gestational age that should tel you when baby was conceived.
Early pregnancy is such an anxious time, even without pre-existing mental health, so I hope you get support soon.

Thank you for explaining this to me, so even if I’m not sure when my last period was, the ultrasound dates should be pretty accurate?
everything matches up and my partner moved into my house in April so I’m not sure where this constant worry has come from about it not being his! It’s draining, hopefully I get some extra support soon.

This definitely sounds like an intrusive OCD thought and well done for spotting that and seeking help @Soontobemummy9 . Early pregnancy is a super hard time for anxiety because it's so uncertain and unknown. Add to that this is unplanned pregnancy with a new partner and you lost your mum around her pregnancy, it makes total sense that you are very anxious. Wishing you all the best for treatment x

What was the length of gap between sleeping with someone else and dp? Was it since your last period?

Think of the generational age as the age of the egg. Day one is when the egg is released, the egg is fertilised on day 14.